We don’t know what will emerge as President Trump’s plan to replace Obamacare, which he has promised to unveil immediately after the 2020 elections. But he has recently endorsed several proposals, and they could provide clues. A group of conservative health policy experts has developed a health care proposal that would hand states blocks of money and a few rules, and encourage them to develop their own health care systems. The plan would require that government-subsidized systems offer every American a choice of a private health plan, a requirement that would probably foreclose a liberal state from enacting a single-payer program and that might require restructuring of some state-run Medicaid programs.